After several hoax e-mails about terrorist attacks in the wake of the Mumbai train blasts, President A P J Abdul Kalam has received an anonymous 'threatening mail', informed sources said on Thursday.

Rashtrapati Bhawan confirmed that a threatening letter had been received by the President on Wednesday and was handed over to intelligence agencies for investigation. The matter is being pursued.

The investigators are also trying to find out who leaked the matter to the media from the Rashtrapati Bhawan.

Sources refused to divulge any details about the nature or contents of the letter or whether the sender's identity has been established or not. They said the investigation will take time because the web portal through which the e-mail was sent. Yahoo! is not an India based company.

Intelligence sources assure that the matter would be settled just like previous such incidents were. A few years ago, a man from Bihar sent live cartridges to President Kalam. The culprit was tracked down and arrested.